A conventional inkjet printing system includes a printhead, an ink supply which supplies liquid ink to the printhead, and an electronic controller which controls the printhead. The printhead ejects ink drops through a plurality of orifices or nozzles and toward a print medium, such as a sheet of paper, so as to print onto the print medium. Typically, the orifices are arranged in one or more arrays such that properly sequenced ejection of ink from the orifices causes characters or other images to be printed upon the print medium. The operation of the printhead is a function of various parameters, including but not limited to, ink type, number of nozzles in the orifice plate, spacing between the nozzles, data transfer rates, among others. In addition, different print cartridges may operate according to different protocols. As such, the printer must utilize the protocol of the print cartridge in order to achieve proper ejection of ink and to prevent damage to the print cartridge.
In an ink jet printer it is desirable to have several characteristics of each print cartridge easily identifiable by a controller. Ideally the identification data should be supplied directly by the print cartridge. The “identification data” provides information to the controller to adjust the operation of the printer and ensures correct operation. The identified characteristics include, but are not limited to, ink color, architecture revision, resolution, number of nozzles in the orifice plate, spacing between the nozzles, among others as described in the previous paragraph. In addition to the above characteristics of the print cartridge, it may be further desirable to characterize each print cartridge during manufacturing and to supply this information to the printer. In this manner, it would be possible compensate for variations in energy supplied to the resistor array in the integrated circuit, ink drop volume, ink drop velocity, missing nozzles, and various other manufacturing tolerances or defects such as orifice plate misalignment or non-planarity and angled orifice holes.
Print cartridges and printers employ electrical interconnects between the cartridge and the printer, so that operation of the print cartridge can be controlled by the printer. The electrical interconnects can be in the form of an interconnect array having a plurality of discrete interconnect pads. The use of replaceable print cartridges in inkjet printers allows the possibility that a user may install or attempt to install a replacement print cartridge that is not designed for use with the user's particular printer or with the particular chute of the particular printer. The installation of a print cartridge into an incorrect chute in a printer can result in dangerous situations where electrical circuits are energized incorrectly, e.g. using the improper protocol or improper signal magnitudes, causing damage to the print cartridge, the printer, or both. This damage may cause substantially loss for users. Therefore, consideration must be given to the prevention of use of a print cartridge that will not operate properly in the chute or printer.
One solution to prevent incorrect use of a print cartridge in a printer is to make each print cartridge with a physically different shape from other print cartridges for other printers or chutes, so that there is no possibility of a printer accepting an incorrect cartridge. This solution requires very different production lines for print cartridges and printers and is consequently costly to implement. Another solution is to have similar print cartridges, but provide unique physical keys on the cartridge and printer so that an incorrect cartridge cannot be inserted into a printer. This solution can be defeated by a user who removes or modifies the physical keys. Yet another solution is to have physically similar print cartridges, and to make sure that the positions of the interconnect pads do not overlap between cartridges intended for different printers or different chutes. This solution becomes unreasonably difficult to implement, as eventually interconnect pad positions will overlap as the number of interconnect pads increases (increasing performance) and/or the size of the interconnect array decreases (decreasing cost).
In addition, it is possible that different types of print cartridges are capable of being inserted into a single chute. In this instance, it is necessary to identify the operating parameters of the print cartridge that is inserted and operate that print cartridge accordingly. To do this, a number of parameters of the print cartridge need to be identified.
As the different types of cartridges and their operating parameters increase, there is a need to provide a greater amount of identification information. At the same time, it is not desirable to add further interconnections to the flex tab circuit to carry such identification information.